docs: def color_process(queue, lock):
      "Receive filenames and get the colors from their images."
      while True:
          block = queue.get()
          if block == config.SENTINEL:
              break
  
          for filename in block:
              try:
                  palette = extract_colors(filename)
              except:  # TODO: it's too broad exception.
                  continue
              lock.acquire()
              try:
                  print_colors(filename, palette)
              finally:
                  lock.release()